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I have a 93 HD Sportster XLH1200. I was having trouble with my front cylinder not firing. Changed plugs worked for a minute then stopped. Replaced wires and now it's firing however this whole time it's been running rich. I could never get the choke completely off. After last start both cylinders were firing but the front was not firing as often. It got hot but not as hot as back. My husband messed with the mixture screw on s&s super e shorty carb. Now the bike just turns over, sometimes tries to start but backfires. I'm posting on here because I am trying to learn and he is zero help. I pulled the new plugs and they are dry and very sooty. I know I need to clean and rebuild the carb but I am worried there could be more. He mentioned something about cylinder being bad? And I keep seeing mentions of timing when I look through the forums. I need some guidance here. I want to RIDE! All help is greatly appreciated.
If your intake manifold rubber gaskets are more than three years old I would replace them before doing anything else. They are notorious for drying up and leaking, causing much grief to the unaware!
You should definitely remove, clean/rebuild the carb, and also change your intake manifold seals, there are 3 of them to change. Try to set the carb back to it's recommended screw settings and jets, then adjust from there. Engine compression or mechanicals are rarely an issue, the motors are pretty bulletproof. If you have not changed manifold seals, it's long overdue.
A compression test is pretty easy on our bikes, that would tell you the condition of your cylinders, which is likely not the problem, but it can't hurt to know.
Timing is preset at the factory, and should not need adjustment. You might check the connector to your module (under triangle cover just rear of battery) and look for any loose connections. It's not likely to be the problem, but it always helps to check.
Be sure to read up on the proper installation of the head to manifold seals. Leave the bolts a bit loose until the carb is positioned, then snug them down, not much torque needed, just hand tight works. Dish soap is recommended to lube the seals, but I've used red grease without issue. Good luck.
John
Last edited by John Harper; Aug 1, 2023 at 12:50 PM.
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